Fats and oils which contain fatty acids are oxidized in the presence of oxygen to hydroperoxides. These hydroperoxides further decompose to form either polymers, gummy materials, aldehydes, ketones or acids. The presence of hydroperoxides and their decomposition products causes fats and oils and foods containing fats and oils to develop off-flavors and malodors.
Antioxidants, for example, the tocopherols, BHA, BHT, TBHQ and citric acid inhibit the oxidation of unsaturated fatty acids, but do not prevent the formation and decomposition of hydroperoxides. Generally, food antioxidants act either by chelating heavy metals which can catalyze autoxidation, or by interrupting the free radical chain mechanisms of autoxidation.
Trivalent phosphorus compounds have been used as antioxidants in plastics, gasoline, and in other non-food products. However, monomeric phosphines are toxic and not suitable for use in edible fats and oils.
It is an object of this invention to provide trivalent phosphorus compounds which are effective in inhibiting the hydroperoxide formation in fatty materials containing fatty acids, especially fats and oils.
It is another object of this invention to provide food antioxidants which are non-digestible and non-absorbable and thus, non-toxic.